Studies will be continued on the role of the circulating catecholamines in regulation of renin release, both in animals with innervated and denervated kidneys, on the effects of arginine vasopressin (AVP) and 1-desamino-8-d-arginine vasopressin (DDAVP) on renin secretion and renal electrolyte excretion in the conscious dog, on the ability of the dog with inferior vena caval constriction to restore and maintain blood pressure during administration of the angiotensin converting enzyme inhibitor (2-D-methyl-3-mercaptopropanyl-L-proline), on the distribution of transport Na-K-ATPase in the kidneys of dogs with congestive heart failure, and the effect of diuretic agents on the distribution of transport Na-K-ATPase. In addition we plan to study factors which regulate renin release in the isolated, perfused rat kidney and in isolated glomeruli. BIBLIOGRAPHIC REFERENCES: Beeuwkes, R. and Brenner, B.M.: The renal circulation. In: The Peripheral Circulation. Johnson, P.A., ed. W.B. Saunders, Inc., N.Y. 1977. Beeuwkes, R., Shahood, J., Chirba, M., and Rosen, S.: Renal Na-K-ATPase inhibition by ethacrynic acid and ouabain: optical and electron probe microanalysis. Abstracts 22nd International Congress of Physiological Sciences, Paris, 1977 (in press).